Analog sampling apparatus for liquid crystal display

Abstract

An analog sampling apparatus for a liquid crystal display device includes: a data driver to generate an analog data voltage; a data output bus line to receive the analog data voltage; a first sampling and holding circuit connected to the data output bus line to compensate an offset voltage in the analog data voltage and to supply the analog data voltage to a data line of a liquid crystal display panel; and a second sampling and holding circuit connected to the data output bus line arranged to sample the analog data voltage while the analog data voltage is supplied to the data line by the first sampling and holding circuit. The first sampling and holding circuit is arranged to supply the analog data voltage while the second sampling and holding circuit samples the analog data voltage, and to sample the analog data voltage while the second sampling and holding circuit supplies the analog data voltage.

1. An analog sampling apparatus of a liquid crystal display device, comprising:
 a data driver to generate an analog data voltage; 
 a data output bus line to receive the analog data voltage; 
 an output node to output the analog data voltage; 
 a first sampling and holding circuit connected to the data output bus line to compensate the analog data voltage for an offset voltage to control a voltage of the output node with the compensated analog data voltage; 
 a second sampling and holding circuit connected to the data output bus line to sample the analog data voltage while the voltage of the output node is controlled by the first sampling and holding circuit, wherein the first and second sampling and holding circuits are arranged to alternately control the voltage of the output node and to sample the analog data voltage; 
 a shift register to sequentially generate a sampling signal; and 
 a timing controller to generate a first control signal having a pulse width of one horizontal period and a period of two horizontal periods, and a second control signal having an opposite phase to the first control signal; an HSP signal generated with an interval of one horizontal period; a B∩HSP signal generated to be at a logic high value at a sampling point of time when the second control signal is a logic high value; a A∩HSP signal generated to be at a logic high value at a sampling point of time when the first control signal is a logic high value, and an RSP signal indicating a pre-charge period and a data supply period of the data line, to control the sampling and holding circuits and to control the data driver and the shift register. 
 
     
     
       2. The analog sampling apparatus according to  claim 1 , wherein the first sampling and holding circuit includes:
 a first switch device to receive the analog data voltage and to be controlled by the B∩HSP signal; 
 a first capacitor connected to the first switch device; 
 a first inverter connected to the first capacitor; 
 a second capacitor connected to the first inverter; 
 a second inverter connected to the second capacitor; 
 a second switch device connected between an output terminal of the first inverter and a node between the first capacitor and the first inverter to be controlled by the second control signal; and 
 a third switch device connected between an output terminal of the second inverter and a node between the second capacitor and the second inverter to be controlled by the second control signal. 
 
     
     
       3. The analog sampling apparatus according to  claim 2 , wherein the second sampling and holding circuit includes:
 a fourth switch device to receive the analog data voltage and to be controlled by the A∩HSP signal; 
 a third capacitor connected to the fourth switch device; 
 a third inverter connected to the third capacitor; 
 a fourth capacitor connected to the third inverter; 
 a fourth inverter connected to the fourth capacitor; 
 a fifth switch device connected between an output terminal of the third inverter and a node between the third capacitor and the third inverter to be controlled by the first control signal; and 
 a sixth switch device connected between an output terminal of the fourth inverter and a node between the fourth capacitor and the fourth inverter to be controlled by the first control signal. 
 
     
     
       4. The analog sampling apparatus according to  claim 3 , further comprising:
 a first transmission gate connected between the output node and a node between the first switch device and the first capacitor to supply the analog data voltage to the output node in response to the first control signal; 
 a first transistor receiving a low potential voltage; 
 a second transistor connected between the first transistor and the output node; 
 a third transistor connected to the output node and to receive a high potential voltage is supplied; 
 a second transmission gate connected between a gate terminal of the first transistor and a node between the third switch device and an output terminal of the first inverter to be controlled by the first control signal; 
 a third transmission gate connected between the output node and a node between the fourth switch device and the third capacitor to supply the analog data voltage to the output node in response to the second control signal; and 
 a fourth transmission gate connected between the gate terminal of the first transistor and a node between the sixth switch device and an output terminal of the fourth inverter to be controlled by the second control signal. 
 
     
     
       5. The analog sampling apparatus according to  claim 4 , wherein the first and second transistors are each an n-type TFT; and the third transistor is a p-type TFT. 
     
     
       6. The analog sampling apparatus according to  claim 2 , wherein the first switch device of the first sampling and holding circuit is arranged to be turned on in response to a B∩HSP signal generated in a high logic at a sampling point of time within a period in which the second control signal is a high logic, to supply an analog data voltage from the data output bus to the first capacitor, and to be turned off to interrupt a current path between an input terminal and the first capacitor when the B∩HSP signal is at logic low. 
     
     
       7. The analog sampling apparatus according to  claim 3 , wherein the fourth switch device of the second sampling and holding circuit is arranged to be turned on in response to an A∩HSP signal generated in a high logic at a sampling point of time within a period in which the first control signal is a high logic, to supply an analog data voltage from the data output bus to the third capacitor, and to be turned off to interrupt a current path between an input terminal and the third capacitor when the B∩HSP signal is at logic low.